Both genes and environmental toxins may act as risk factors for Parkinson's disease (PD), but their potential interplay remains poorly understood. This proposal seeks to investigate gene-environment interactions that are potentially relevant to PD using the model organism Drosophila melanogaster. Attention will be directed on genes and toxins associated with PD that affect mitochondrial dysfunction, protein ubiquitination and dopamine homeostasis. Over-expression of the Drosophila vesicular monoamine transporter (DVMAT) has been shown to protect against the neurotoxic effects of at least one mutant gene associated with PD (parkin), and at least one pesticide (rotenone) that selectively kills dopaminergic neurons. This study will therefore test the hypothesis that the neuroprotective effects of VMAT will extend to a different toxin, paraquat, thought to act by a different mechanism than rotenone, and whether this requires its localization to synaptic vesicles and if it is required at a specific time relative to neurotoxic insults. Studies here have shown that over-expression of mutant forms of parkin can cause dopaminergic cell degeneration in flies. If mutations in parkin function as a risk factor for PD, then additional environmental agents may enhance this risk. This study will test this hypothesis using rotenone, paraquat and other agents. Parallel experiments for gene-environment interactions will be performed with the PD related gene, pink1. Finally, already established pink mutant phenotypes will be used to screen for agents that rescue the neurotoxic effects of mitochondrial dysfunction.